Experimental in nature, the Spirit was only supposed to last a short time. Instead, it long outlasted its expected shelf life, and it spawned a new generation of rovers that ushered in a new era of space exploration.

The new Big-3 era was really only supposed to last three years. The Celtics were supposed to have a very short championship window and, when the three years were over, they would have to start anew around Rajon Rondo and whatever other draft picks may have matured into contributors along the way. Instead, they have now nearly doubled their life expectancy, entering this season as one of a handful of teams who should not be making any plans for June golf outings. Meanwhile, the success of the original Big-3 has spawned copycats around the league who saw Boston's immediate, dramatic turnaround and want to experience it themselves.

It has actually been a pretty remarkable run for the Celtics. It has not always been pretty, and it has had its share of controversy and heartbreak, but no one in 2008 would have predicted the Celtics would still be in the championship mix in 2013. But while the Celtics run as one of the NBA's elite is not over, the era that started it all is.

The 2012-2013 Celtics season is the first not to be powered by the Paul Pierce, Kevin Garnett, Ray Allen triumvirate since this whole crazy run kicked off. The new Big-3 era is over, and the Celtics have transitioned from a “Big 3” to a more complete team that will rely on significant contributions from more players as the two eldest statesmen, Garnett and Pierce, pare their minutes down in an effort to stay fresh and effective for eight grueling NBA months. And they are doing it behind a new leader.

Rajon Rondo.

His ascension to the role is perhaps the biggest story line in Boston. Doc Rivers has said it. Danny Ainge has said it. So have Garnett and Pierce. Everyone in Green is making sure the world knows that Rajon Rondo is the leader of this team.

Well, everyone except Rondo.

"I’m not the team leader," Rondo said Monday before the team departed for Turkey. "Everybody keeps saying that, [Celtics president of basketball operations] Danny [Ainge] put that pressure on me [by calling Rondo the team's best player]. There’s 15 guys on this team. Paul [Pierce has] been here for 15 years and I’m still following in his footsteps. I might be a leader as far as point guard wise, and I’ll accept that role. But three or four guys are the leaders — Kevin, Paul, and even [Jason Terry]. They are the veterans. I’m going to lead the young guys, and try to lead the older guys as well. But I’m still following."

At this delicate time in Celtics history, as they try to balance a combination rebuild/reload with young and old players, one thing is clear about this: everyone here is right.

The guys not named Rondo are right about him stepping up in to a new role. He IS their leader. On the court, the ball is in his hands more than any other. He orchestrates offenses, often independent of Doc Rivers, who is content to let his point guard's CPU process everything he sees before him. And like Garry Kasparov flying through move after move in his head before placing a fingertip on a bishop, Rondo cycles through options at a dizzying mental pace before actually triggering the offense.

Rondo's eyes may as well be motion-detecting cameras, picking up flinches, sideways glances, and missed assignments within milliseconds of them happening. And he has no qualms about letting anyone, from Kevin Garnett to Dionte Christmas, know that what's happening, when it will happen, or why they missed it.

But Garnett, Pierce and Terry have been through the wars. They are still among the best in the business even at combined 106 years old. You do not hang around the NBA into your mid 30's in very important roles unless you know a little something about the game. These guys have forgotten things about basketball that Rondo hasn't learned yet. Of course they will lead.

The distinction with "Rondo is our leader," though, is that they are not only willing to listen to him, they are willing to accept that what he's saying is not some half-cocked guess. If Rondo pulls Garnett and Pierce aside and says "I see this. If you go here, you go there, and do these things, we're getting a basket," they nod and say OK rather than ask "are you sure?"

And this is what it all boils down to, really. It is not about the team saluting Rondo as he walks in the door, falling in line for inspection, and waiting for his inspirational words of wisdom. It is about trust. At 26 years old, Rondo has earned the unequivocal trust of his Hall of Fame teammates. They trust him to see things, say things, and tell them things that will lead to the team's ultimate success. For Garnett and Pierce, the pressure is off.

And hell, sometimes, when you have been "the man" your entire career, it is not a bad break every once in a while to let someone else handle the spotlight as you slip out the side door. It's nice to know that, as the last sands drip through the hourglass of your career, the team you are leaving is in good hands.

Rajon Rondo is by no means a polished diamond. Within the past calendar year, he has thrown a ball, and his body, at referees. He is still prone to gambling on defense and quiet tantrums until we see that he is not. A pre-season's worth of glowing Rondo scripture by no means makes the man infallible.

But it does mark another step along the way to a more complete, more mature player. Perhaps Rondo's career is a bit like running up a big sand dune. Every stride brings progress, and then a little slide. The key, though, is to keep going, and realize that it is a lot of hard work and a bit of frustration to get to where you need to be.

This is a pivotal year for Rajon Rondo and the Boston Celtics. He has had the role of leader, and the trust inherent with that role, bestowed upon him from all who matter in Boston. If Rondo can prove that he is worthy, that the blips and blunders of the past are truly part of his past, the this year's Celtics team, and those teams for the next near decade, will be led quite well.

What will the Rajon Rondo-led Celtics look like? Let us know in the comments below or on Twitter by using the hashtag #CelticsDay.